Pro-dynorphin is the common precursor for three opioid peptides: dynorphin A, dynorphin B, and alpha-neo-endorphin. Although there is considerable information on the anatomical distribution of these peptides, the structure of the precursor, and the sequences of the end products derived from this precursor, relatively little is known about the postnatal ontogeny of this system, the steps involved in the post-translational processing of pro-dynorphin, or the mechanisms for regulating region specific proteolytic processing of pro-dynorphin. This proposal will consider two issues: 1) the postnatal ontogeny of pro-dynorphin in the magnocellular/posterior pituitary system and the striato-nigral system; 2) determine whether postnatal neurons obtained from the hypothalamus and striatum are suitable for in vitro monolayer tissue culture studies. The initial studies will monitor the steady state levels of pro-dynorphin-related end products in the posterior pituitary and substantia nigra during postnatal development. These studies will involve radioimmunoassay analyses in conjunction with gel filtration chromatography and high performance liquid chromatography. The in vitro studies will test the viability of different aged neonatal neurons in monolayer culture with a pulse radiolabeling paradigm. Analyses will be done by immunoaffinity column chromatography in conjunction with SDS polyacrylamide gel electrophoresis.